Evaporation is simply molecules breaking into the air from a liquid. Molecules must achieve two things--'lifting' their weight, and interactions leaping with other molecules. In terms of size, smaller molecules should evaporate more quickly than bigger ones. With this in mind, ethanol molecules are larger than waters (see webpage above for observable oddities of water). Going on that ALONE, we would predict that of the two, ethanol should evaporate more slowly . However, this is not what is observed . Ethanol feels cooler on the skin and evaporates more quickly. We must look elsewhere for another factor! The secret lies in hydrogen interactions. water makes a ton of them; each of its atoms makes at least one. This creates a web of interactions holding each water molecule to several others-- and preventing evaporation. This is why water has an abnormally high boiling point for a small molecule. And it's related to the reason that unlike most solids, ice floats on its liquid (water). While we think of water as 'normal', it's actually a pretty outlandish liquid.

part 1: the half-life of the element is 22 years.

part 2: it will take 132.02 year for the sample to decay from 308.0 g to 4.8125 g.

explanation:

part 1: there are two ways to determine the half life time.

first way: the half life time can be determined directly from its definition as it is the time required for the sample to decay to its half concentration.

from the data the initial concentration was 45.0 g and decayed to its half value (22.5 g) in 22.0 years.

second way: the radio active decay is considered first order reaction so we can use the laws of first order reactions.

k = (1/t) ln (a/a-x), where k is the rate constant of the reaction,

t is the time of the reaction

a is the initial concentration of the reactant

a-x is the remaining concentration at time (t)

a = 45.0 g the initial concentration at t = 0 year.

at t = 22 year, a-x = 22.5 g

then k = (1/22 year) ln (45.0 g/ 22.5 g) = 0.0315 year-1.

the half-life time (t1/2) = ln 2/ k = 0.693/ k =0.693/ 0.0315 = 22 years.

part 2:

using the same law k = (1/t) ln (a/a-x),

using the given data; a = 308.0 g and a-x = 4.8125 g and the calculated k from the part 1 (k = 0.0315 year-1)

t = (1/k) ln (a/a-x) = (1/0.0315) ln (308.0/ 4.8125) = 132.02 years